Multicontact connectors have been widely used by the electrical and communications industry to interconnect circuit paths of component electrical circuits to form a larger composite electrical circuit. When component circuits are interconnected by connectors the composite circuit may fail to operate either from a failure of one of the component circuits or from a poor connection between contact terminals of the connector used to interconnect the circuit paths. The later type of circuit failure quite often results from a poor or the absence of a connection between mating connector contact terminals. This type of connector failure may arise either because some particulate matter or film formation has appeared on the contact surfaces of the connectors so that the contacts may fail to make electrical connection.
Often times during the manufacture of connectors a contamination film or foreign material inadvertently appears on ones of the contact terminals of connectors. Subsequently, the connectors are installed in or on electrical equipment to provide a means to interconnect component electrical circuits that may be added or installed after the electrical equipment has been shipped and located on customer premises. When electrical component circuits are later installed the contamination film and foreign material appearing on the contact terminals result in a poor electrical connection between mating connector contact terminals that cause failure of the composite electrical circuit. Locating this type of circuit failure is extremely difficult.
Measurement techniques and apparatus have been developed to measure the electrical resistance of conducting surfaces. These measurement techniques, sometimes referred to as a so-called four-point contact resistance measurement, are accomplished by applying a known constant current to two outer points of a contact area and measuring the voltage appearing between two inner points of the same contact area. The contact resistance may then be readily ascertained from the value of the known current and measured voltage. A problem with the apparatus used to make a four-point contact resistance measurement is that sufficient space must be available in order to gain access to the measurement points.
Apparatus has been disclosed for use with connectors to measure the resistance between printed patterns on a circuit board and the connector contact terminals. The prior art connector measuring apparatus comprises a pair of first probes for engaging a conducting finger pattern on the circuit board and a pair of second probes for engaging a contact terminal of the connector. Measurement of the contact resistance between the connector contact terminal and the circuit board conducting finger pattern is made by applying a known constant current between one of the first and second probes and determining the voltage between the other one of the first and second probes. The aforementioned problem is highlighted in that a difficulty with this type of apparatus is that the two pairs of probes are intended for use in measuring the contact resistance between a connector contact and the circuit board conducting finger pattern. A further difficulty occurs in this type of apparatus in that the probe apparatus intended for use with circuit board edge connectors is too bulky and cumbersome for use in detecting and measuring contamination films and foreign material on a contact terminal of a pin insertion type of connector.
Accordingly, a need exists in the art for probe apparatus arranged for use with measuring apparatus to detect and measure contamination films on connector contact terminals. A need also exists for probe apparatus arranged for use in detecting and measuring contamination films and foreign material that inadvertently occur on contact terminals during the manufacture of pin insertion type of connectors.